Has he been doing it ever since you got him or just started? You could put some cardboard toilet rolls in and half an egg box maybe and see if he chews those instead. You can also make little treat parcels out of toilet rolls - that might distract him a bit. This video shows how (along with other toilet roll tubes).
https://www.youtube.com/results?sear...s+for+hamsters
Is the place you have the cage ok? ie not right next to window where it could get hot or draughty. No dogs nearby? Sorry I'm asking so many questions lol!